Types of Triangles: Finding the size of angles in a triangle

Calculate the size of angle X given that the triangle is equilateral.

Remember that the sum of angles in a triangle is equal to 180.

In an equilateral triangle, all sides and all angles are equal to each other.

Therefore, we will calculate as follows:

$x+x+x=180$

$3x=180$

We divide both sides by 3:

$x=60$

60

Below is an equilateral triangle.

Calculate X.

Since in an equilateral triangle all sides are equal and all angles are equal. It is also known that in a triangle the sum of angles is 180°, we can calculate X in the following way:

$X+5+X+5+X+5=180$

$3X+15=180$

$3X=180-15$

$3X=165$

Let's divide both sides by 3:

$\frac{3X}{3}=\frac{165}{3}$

$X=55$

55

ABC is an equilateral triangle.Calculate X.

Since this is an equilateral triangle, all angles are also equal.

As the sum of angles in a triangle is 180 degrees, each angle is equal to 60 degrees. (180:3=60)

From this, we can conclude that: $60=8x$

Let's divide both sides by 8:

$\frac{60}{8}=\frac{8x}{8}$

$7.5=x$

7.5

Find all the angles of the isosceles triangle using the data in the figure.

In an isosceles triangle, we remember that the base angles are equal to each other, so angles C and B are equal to each other:

$C=B=62$

Now we can calculate the vertex angle.

We remember that the sum of angles in a triangle is equal to 180 degrees, therefore:

$A=180-62-62=56$

The angle values in the triangle are: 62, 62, 56

62, 62, 56

Find all the angles of the isosceles triangle using the data in the figure.

Let's remember that in an isosceles triangle, the base angles are equal to each other.

In other words:

$C=B$

Since we are given the vertex angle, which is equal to 70 degrees, we'll recall that the sum of angles in a triangle is equal to 180 degrees.

Now let's find the base angles in the following way:

$180-70=110$

$110:2=55$

Therefore, the angle values in the triangle are: 55, 55, 70

70, 55, 55

Find all the angles of the isosceles triangle using the data in the figure.

In the triangle shown in the diagram, we notice that one angle is a right angle equal to 90 degrees.

We'll remember that in an isosceles right triangle, the base angles are equal to each other.

Since the sum of angles in a triangle is equal to 180, we can calculate the angles as follows:

$180-90=90$

$90:2=45$

Therefore, the angle values in the triangle are: 90, 45, 45

90, 45, 45

Look at the isosceles right triangle below. What are its angles?

Let's remember that the sum of angles in a triangle is equal to 180 degrees.

In a right triangle, there is one right angle equal to 90 degrees.

In an isosceles triangle, the base angles are equal to each other.

Therefore, we can calculate this in the following way:

$180-90=90$

$90:2=45$

In other words, the angle values in this triangle are: 90, 45, 45

90, 45, 45

What type of triangle appears in the drawing?

To determine which type of triangle we are dealing with, let's calculate angle alpha based on the fact that the sum of angles in a triangle is 180 degrees.

$\alpha=180-30-10=140$

Since alpha is equal to 140 degrees, the triangle is an obtuse triangle.

Obtuse triangle

Find all the angles of the isosceles triangle using the data in the figure.

Since we are given that the triangle is isosceles, we will remember that the base angles are equal to each other.

That is:

$B=C=50$

Now we can calculate the vertex angle.

Since the sum of angles in a triangle is equal to 180 degrees, we will calculate the vertex angle as follows:

$A=180-50-50=80$

Therefore, the values of the angles in the triangle are: 80, 50, 50

$A=80,C=50$

Find all the angles of the isosceles triangle using the data in the figure.

In an isosceles triangle, the base angles are equal to each other, meaning:

$B=C$

Since we are given angle A, we can calculate the base angles as follows:

Let's remember that the sum of angles in a triangle is equal to 180 degrees.

$180-50=130$

$130:2=65$

$B=C=65$

$B=65,C=65$

What type of triangle appears in the drawing?

Obtuse triangle

What type of triangle appears in the drawing?

Acute triangle

What type of triangle appears in the drawing?

It is not possible to calculate

ABC is an equilateral triangle.

How big is angle $∢ACB$?

60°